Bond surface testing apparatus and method

ABSTRACT

A bond surface testing apparatus and method are presented. The bond surface testing apparatus comprises a solution chamber; a plurality of solution containers located in the solution chamber; a plurality of microfluidic pipettes; and an information capture module. Each solution container in the plurality of solution containers includes a microfluidic pipette in the plurality of microfluidic pipettes. A number of the plurality of microfluidic pipettes has a non-circular cross-section. The information capture module is physically associated with the solution chamber and is configured to capture information relating to bonding surface properties of the bonding surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/023,682 filed Feb. 9, 2011, status allowed, the entiredisclosure of which is incorporated by reference herein.

TECHNICAL FIELD

The disclosure generally relates to apparatuses and methods for testingbonding suitability of structural composite bonding surfaces. Moreparticularly, the disclosure generally relates to a bond surface testingapparatus and method capable of measuring characteristics of a bondingsurface via surface energies that are activated on the bonding surfaceand then converted into a series of complex mathematical algorithmswhich output a calculated quality bonding factor that is based on thethree-dimensional wettability surface energies of the bonding surfaceand indicates whether the bonding surface is suitable for bonding.

BACKGROUND

Currently, prepared structural composite bonding surfaces which areintended for structural bonding with another material are notcertifiable prior to bonding. Thus, much expense may be wasted in scrapsdue to the poor bonding quality of bonding surfaces on composites.Conventional design and maintenance practices may not solely rely on theperformance of a bonded joint or repair on composites for structuralcertification. As bonded composite structures become more common as away to reduce weight and improve airframe performance in modernaircraft, reliable methods may be required to directly certify thequality of the bonded joints between composites without addingadditional contaminants that may negate their structural benefits. Inaddition, the use of structural bonding repair techniques, compared tomechanically-fastened joints, may become more viable as a long-termrepair solution. Like composite bonded structures, bonded repairs mayrequire a certification method to ensure the structural quality of thebonding surfaces which form the bond between composites.

One current solution for ensuring that an optimum structural bondsurface exists on a composite structure may rely on tight processcontrols and the skill of technicians to ensure quality and consistency.In some cases, cleanliness and roughness of the bonding surface may bemeasured and compared to an acceptable range to provide an inlineprocess check. However, none of the known available methods can quantifyand certify the bonding surface itself prior to structural bonding. Sucha certification method would create confidence in the long-termdurability of the bonded joint between composites after the structurewhich includes the bonded joint enters service. Individual surfacecharacterization techniques that provide information on a single surfacevariable, such as surface roughness or active contaminants viaprofilometry or X-ray photoelectron spectroscopy (XPS), respectively,exist. However, both profilometry and XPS typical data may not quantifythe structural bonding surface in terms of readiness to meet long-termstructural joint durability, static strength and damage tolerancecapability.

Conventional methods may not provide quantifiable engineering datarelated to the just-prepared structural bonding barrel surface qualityor its bond durability. Moreover, such methods may not be compatible forlocalized use on the composite structures which are being bonded.Additionally, the existing techniques may not account for thepotentially wide variations of the measured results on the structuralbonding surface. Even a minimum of engineering data, such as surfaceroughness, for example, can vary greatly when the bonding surface isprepared per procedure via hand sanding methods, grit blasting, andlaser techniques.

Therefore, a bond surface testing apparatus and method are needed whichare capable of measuring characteristics of a bonding surface viasurface energies that are activated on the bonding surface and thenconverted into a series of complex mathematical algorithms which outputa calculated quality bonding factor that is based on thethree-dimensional wettability surface energies of the bonding surfaceand indicates whether the bonding surface is suitable for bonding.

SUMMARY

In one illustrative embodiment, a bond surface testing apparatus fortesting bonding suitability of a bonding surface is present. The bondsurface testing apparatus comprises a solution chamber; a plurality ofsolution containers located in the solution chamber; a plurality ofmicrofluidic pipettes; and an information capture module. Each solutioncontainer in the plurality of solution containers includes amicrofluidic pipette in the plurality of microfluidic pipettes. A numberof the plurality of microfluidic pipettes has a non-circularcross-section. The information capture module is physically associatedwith the solution chamber and is configured to capture informationrelating to bonding surface properties of the bonding surface.

In another illustrative embodiment, a bond surface testing apparatus fortesting bonding suitability of a bonding surface is present. The bondsurface testing apparatus comprises: a solution chamber, a plurality ofsolution containers located in the solution chamber, a plurality ofmicrofluidic pipettes, a plurality of solutions in the solution chamber,a plurality of stand-offs, an information capture module, a datatransfer pathway, a plurality of analysis modules, and a structuralwettability factor prediction module. Each solution container in theplurality of solution containers includes a microfluidic pipette in theplurality of microfluidic pipettes. A number of the plurality ofmicrofluidic pipettes has a non-circular cross-section. Eachmicrofluidic pipette is configured to dispense a solution in theplurality of solutions onto the bonding surface. The plurality ofstand-offs are configured to engage the bonding surface. The informationcapture module is carried by the plurality of stand-offs and configuredto capture information relating to bonding surface properties of thebonding surface. The data transfer pathway interfaces with theinformation capture module. The plurality of analysis modules interfaceswith the data transfer pathway and is configured to analyze the bondingsurface properties of the bonding surface. The structural wettabilityfactor prediction module interfaces with the data transfer pathway andis configured to predict a structural wettability factor based on thebonding surface properties.

In yet another illustrative embodiment, a bond surface testing method ispresented. A plurality of solutions are provided. Functional groups on abonding surface are activated by dispensing the plurality of solutionsonto the bonding surface, in which at least one solution of theplurality of solutions is dispensed in a non-circular shape onto thebonding surface. The bonding surface properties on the bonding surfaceare analyzed. A structural wettability factor is predicted based on thebonding surface properties.

The features and functions can be achieved independently in variousembodiments of the present disclosure or may be combined in yet otherembodiments in which further details can be seen with reference to thefollowing description and drawings.

BRIEF DESCRIPTION OF THE ILLUSTRATIONS

FIG. 1 is an exploded perspective view of an illustrative example of thebond surface testing apparatus;

FIG. 2 is a perspective view of an illustrative example of the bondsurface testing apparatus;

FIG. 3A is an illustration of a perspective view of the bond surfacetesting apparatus and a composite structure tested for bondingproduction quality readiness;

FIG. 3B is a top view of a composite structure tested for bondingproduction quality readiness using solutions having non-circular shapesdispensed by an illustrative example of the apparatus;

FIG. 4 is a flow diagram of an illustrative example of the bond surfacetesting method;

FIG. 5 is a functional block diagram which illustrates operation of anillustrative example of the bond surface testing apparatus;

FIG. 5A is a flow diagram which summarizes an illustrative example of abond surface testing method;

FIG. 5B is a flow diagram which illustrates operation of an illustrativeexample of the bond surface testing apparatus;

FIG. 6 is an illustration of a flow diagram of an aircraft productionand service methodology; and

FIG. 7 is an illustration of a block diagram of an aircraft.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and isnot intended to limit the described embodiments or the application anduses of the described embodiments. As used herein, the word “exemplary”or “illustrative” means “serving as an example, instance, orillustration.” Any implementation described herein as “exemplary” or“illustrative” is not necessarily to be construed as preferred oradvantageous over other implementations. All of the implementationsdescribed below are exemplary implementations provided to enable personsskilled in the art to make or use the embodiments of the disclosure andare not intended to limit the scope of the embodiments of the disclosurewhich are defined by the claims. Furthermore, there is no intention tobe bound by any expressed or implied theory presented in the precedingtechnical field, background, brief summary or the following detaileddescription.

The disclosure is generally directed to a bond surface testing apparatuswhich may activate surface energies of functional groups on a bondingsurface and then analyze various chemical and mechanical bonding surfaceproperties using a series of complex mathematical algorithms. When asolution activates a functional group on a bonding surface, the solutionmay interact with the functional group. This interaction may affect thebehavior of the solution on the bonding surface. The functional groupswhich are activated may be those which are involved in bonding of thebonding surface with a second bonding surface. The apparatus may matchthe analyzed bonding surface properties of the bonding surface withthree-dimensional wettability curves to determine convergence of thebonding surface properties with the three-dimensional wettabilitycurves. Based on the convergence of the measured and analyzed bondingsurface properties with the three-dimensional wettability curves, theapparatus may output a calculated quality bonding factor. The outputtedquality bonding factor may indicate the bonding suitability of thebonding surface. Accordingly, the quality bonding factor may indicatewhether the tested bonding surface on the structure is ready forproduction bonding or repair bonding with another structure oralternatively, whether the bonding surface requires preparation prior tobonding. In some applications, the quality bonding factor may be used tocertify the bonding suitability of a bonding surface.

In some embodiments, the apparatus may be a portable handheld apparatus.The apparatus may be compact in design and utilized on a factory or shopfloor for quick turnaround of both measurements of bonding engineeringdata and decisions related to the bonding suitability of a preparedstructural composite surface for the operational life of the structure.

The apparatus may include integrated device components and process stepswhich may include multiple known solutions, for example, a complexsolution chamber with multiple solution containers containing the knownsolutions and capable of dispensing the known solutions in predeterminedvolumes onto a bonding surface of a structure to activate surfaceenergies of functional groups on the bonding surface as well as variousanalysis modules for analyzing bonding surface properties of the bondingsurface. In some embodiments, the analysis modules of the apparatus mayinclude a functional group analysis module for analyzing the functionalgroups on the bonding surface, a surface energy analysis module foranalyzing the surface energies of the functional groups on the bondingsurface, and a chemical-mechanical analysis module for computing themicro-chemical mechanics forces present on the bonding surface. Theapparatus may further include a structural wettability factor (qualitybonding factor) prediction module for prediction of the convergence ofthe three-dimensional wettability curves with the bonding surfaceproperties which are based on the functional group analysis, the surfaceenergy analysis and the chemical-mechanical characteristic analysis ofthe bonding surface, and a structural wettability factor printer forprinting go/no-go quality bonding factor (Ø) which indicates bondingsuitability based on the convergence of the three-dimensionalwettability curves with the bonding surface properties.

Referring to FIGS. 1 and 2, an illustrative example of the bond surfacetesting apparatus, hereinafter apparatus, is generally indicated byreference numeral 100. The apparatus 100 may be used to determine thebonding suitability of a bonding surface (not shown) on a structuralcomposite bonding element (not shown). In some applications, thestructural composite bonding element may be a component of an aircraftfuselage, for example and without limitation. The apparatus 100 may beapplicable to certification of the bonding surface of a structuralcomposite bonding element in order to ensure the quality of structuralbonds in which the structural composite bonding element is bonded toanother bonding surface in production or repair of a structure.

As will be hereinafter further described, the apparatus 100 may beconfigured to contain and dispense solutions 128 having known chemicalcharacteristics or properties onto a bonding surface 102 of a compositestructure 101. The solutions 128 dispensed onto the bonding surface 102of the composite structure 101 may activate surface energies offunctional groups on the bonding surface 102. The functional groupswhich are activated on the bonding surface 102 may be the functionalgroups which would be involved in bonding of the bonding surface 102 toanother bonding surface. The activated surface energies of thefunctional groups on the bonding surface 102 may substantially mimic thesurface energies of the functional groups on the bonding surface, thebonding suitability of which is to be tested.

Using mathematical algorithms, the apparatus 100 may be configured toanalyze bonding surface properties which may include analysis of thefunctional groups, the surface energies of the functional groups whichare activated on the bonding surface 102 by the known solutions 128, andthe micro-chemical mechanics forces present on the bonding surface 102.The apparatus 100 may be configured to predict convergence ofthree-dimensional wettability tension surface energy curves based on theanalyzed bonding surface properties of the bonding surface 102 bymatching the three-dimensional wettability curves to the bondingproperties. The apparatus 100 may additionally be configured toformulate a bonding quality factor phi (Ø) which indicates bondingsuitability based on the convergence of the three-dimensionalwettability curves with the bonding properties. In some embodiments, theapparatus 100 may be configured to print the bonding quality factor (Ø).

The apparatus 100 may include a solution chamber 110. Multiple solutioncontainers 111 may be provided in the solution chamber 110. The solutioncontainers 111 may be arranged in adjacent relationship with respect toeach other in the solution chamber 110. Each of the solution containers111 may be configured to contain a known solution of solutions 128 whichwill be used to activate surface energies of chemical functional groupson a bonding surface 102 of a composite structure 101. Bonding surfaceproperties which may include surface energies of the functional groupsand the micro-chemical mechanics forces present on the bonding surface102 may be analyzed and matched with three-dimensional wettabilitycurves using mathematical algorithms. The apparatus 100 may beconfigured to predict the convergence of the three-dimensionalwettability curves with the bonding surface properties. Based on theconvergence of the three-dimensional wettability curves with the bondingsurface properties, the apparatus 100 may be configured to predict thebonding suitability of a bonding surface on a structural compositebonding element (not shown) which is represented by the bonding surface102 of the composite structure 101.

In some applications, the composite structure 101 may be a travelerelement having the bonding surface 102 which mimics the bondingproperties of the functional groups on the bonding surface being tested.Each of the solution containers 111 may include a microfluidic pipetteand activator 112 which is configured to dispense a selected volume ofthe solutions 128 from the solution containers 111 onto the bondingsurface 102. At least one of the shape of the dispensed solutions 128and the material of the dispensed solutions 128 may affect theactivation of the functional groups of the bonding surface 102.

As used herein, the phrase “at least one of,” when used with a list ofitems, means different combinations of one or more of the listed itemsmay be used and only one of each item in the list may be needed. Forexample, “at least one of item A, item B, or item C” may include,without limitation, item A or item A and item B. This example also mayinclude item A, item B, and item C or item B and item C. The item may bea particular object, thing, or a category. In other words, at least oneof means any combination of items and number of items may be used fromthe list but not all of the items in the list are required.

As the shape of the dispensed solutions 128 may affect the activation ofthe functional groups of the bonding surface 102, changing the shape ofthe dispensed solutions 128 may change the activation of functionalgroups. Some shapes may be more effective at activating specificfunctional groups. Accordingly, a shape for a drop of the dispensedsolutions 128 may be selected based on the composite material ofcomposite structure 101. For example, the shape of the crystallinity ofa composite structure 101 or the arrangement of functional groups of thecomposite structure 101 may influence a desired shape for a drop of thedispensed solutions 128.

In some examples, when composite structure 101 is an epoxy basedcomposite, at least one of dispensed solutions 128 may have a squareshape. In some examples, when composite structure 101 is a bismaleimidebased composite, at least one of the dispensed solutions 128 may have acircular shape. In some examples, when composite structure 101 is apolyimide based composite, at least one of the dispensed solutions 128may have an elliptical shape. In some examples, when composite structure101 is a polyether ether ketone based composite, at least one of thedispensed solutions 128 may have a hexagonal shape. In some examples,when composite structure 101 is a poly either imide based composite, atleast one of the dispensed solutions 128 may have an octagonal shape. Insome examples, when composite structure 101 is a polycarbonate basedcomposite, at least one of the dispensed solutions 128 may have atrapezoidal shape.

A shape of the dispensed solutions 128 may be influenced by the shape ofthe microfluidic pipette dispensing the fluid. For example, when thedesired shape of the dispensed solutions 128 is non-circular, thecross-section of the microfluidic pipette may be non-circular. In someillustrative examples, at least one microfluidic pipette may beconfigured to dispense a solution as a droplet having a non-circularshape.

FIG. 3B is a top view of a composite structure tested for bondingproduction quality readiness using solutions having non-circular shapesdispensed by an illustrative example of the apparatus. As shown in FIG.3B, dispensed solutions 128 have an elliptical shape.

Accordingly, the solutions 128 can be selectively dispensed from thesolution containers 111 onto the bonding surface 102 to activate theknown surface energies of the functional groups and create themicro-chemical mechanics forces present on the bonding surface 102 in amanner which corresponds to the surface energies and micro-chemicalmechanics forces of the functional groups on the bonding surface whichis to be tested.

The apparatus 100 may include an information capture module 116 in FIGS.1-2. The information capture module 116 may be configured to captureinformation which relates to the bonding surface properties of thebonding surface 102. As depicted, the information capture module 116 isphysically associated with the solution chamber. When one component is“physically associated” with another component, the association is aphysical association in the depicted examples. For example, a firstcomponent may be considered to be physically associated with a secondcomponent by at least one of being secured to the second component,bonded to the second component, mounted to the second component, weldedto the second component, fastened to the second component, or connectedto the second component in some other suitable manner. The firstcomponent also may be connected to the second component using a thirdcomponent. The first component may also be considered to be physicallyassociated with the second component by being formed as part of thesecond component, extension of the second component, or both.

In some illustrative examples, the information capture module 116 mayinclude a number of optical sensors. As used herein, “a number of” meansone or more items. For example, a number of optical sensors is one ormore optical sensors. In some of these examples, the information capturemodule 116 may include nano-functionalized optic sensors.Nano-functionalized optic sensors are sensors that comprise nanoparticles. Optical sensors having nanoparticles may have more desirablefunctionality. For example, optical sensors having nanoparticles mayresult in a better resolution in capturing contact angles.

In some illustrative examples, the information relating to the bondingsurface properties of the bonding surface 102 may include a contactangle. In some examples, the information capture module 116 may capturea two-dimensional contact angle. A two-dimensional contact angle maycomprise measurements from two different perspectives.

In some illustrative examples, a two-dimensional contact angle mayinclude measurements of a droplet of one of the solutions 128 relativeto the bonding surface 102. In one illustrative example, atwo-dimensional contact angle may include a measurement from direction134 of FIG. 1. As depicted, direction 134 of FIG. 1 is substantiallyperpendicular to the bonding surface 102. In another illustrativeexample, a two-dimensional contact angle may include a measurement fromdirection 136 of FIG. 1. As depicted, direction 136 of FIG. 1 issubstantially parallel to the bonding surface 102.

In some illustrative examples, the information capture module 116 maycapture information related to the shape of droplets of the solutions128. Specifically, the information capture module 116 may captureinformation related to the shape of the droplets of the solutions 128from direction 134 of FIG. 1.

Stand-offs (or support for forming a solution clearance gap) 117 inFIGS. 1-3B may interface with the information capture module 116. Thestand-offs 117 may be configured to engage the composite structure 101during operation of the apparatus 100.

A functional group analysis module 120, a surface energy analysis module121, a chemical-mechanical analysis module 122, a structural wettabilityfactor prediction module 123 and a structural wettability factor printer124 in FIGS. 1-2 may interface with the information capture module 116through a data transfer pathway 126 in FIG. 1. Data transfer pathway 126is the medium used to provide communications links between variousmodules connected together within apparatus 100. Data transfer pathway126 may include connections, such as wire, wireless communication links,or fiber optic cables. In some embodiments, a battery 125 in FIGS. 1-2may interface with the structural wettability factor printer 124 andother components of the apparatus 100.

A set of the known solutions 128 may be developed for each of thestructural composite bonding elements, the bonding suitability of whichare to be tested using the apparatus 100. The solutions 128 may bedeveloped according to previously-identified surface energies andwettability tension data of the bonding surfaces of the elements priorto bonding. For example and without limitation, structural bismaleimide(BMI) composite surface (primarily the BMI matrix material) have bothdispersive, polar and modified luftiz acid-base surface energies on thestructural composite bonding element which is to be bonded to anothersurface. Accordingly, the solutions 128 which are dispensed onto thebonding surface 102 may include chemical characteristics which impartthe corresponding bonding surface properties (surface energies andmicro-chemical mechanics forces) to the functional groups on the bondingsurface 102. The apparatus 100 may computationally combine thestructural BMI bonding surface properties of the functional groups withthe matching wettability tension curves of the structural compositebonding element to formulate a quality bonding factor (Ø). The qualitybonding factor (Ø) may indicate whether the prepared bonding surface ofthe element is ready to be bonded.

In application of the apparatus 100, the bonding surface 102 of thecomposite structure 101 may be treated with the solutions 128 with knownchemistries relative to the surface energies of functional groups on thebonding surface of the structural composite bonding element which is tobe tested. After treatment with the solutions 128, the bonding surface102 may include activated functional groups. The activated functionalgroups may be similar to those functional groups used in bonding thecomposite structure 101 to another element. In some examples, theactivated functional groups may be similar to those of the adhesivewhich is used to bond the composite structure 101 to another element.

The material of composite structure 101 may be selected from epoxides,bismaleimides, polimides, polyether ether ketone, polyehterimides,polysulfone, polycarbonate, or other suitable composite materials. Whencomposite structure 101 is an epoxide composite, the solutions will beselected to activate the epoxide functional group. When compositestructure 101 is a bismaleimide composite, the solutions will beselected to activate the maleimide functional group. When compositestructure 101 is a polyimide composite, the solutions will be selectedto activate the imide functional group. When composite structure 101 isa polyether ether ketone composite, the solutions will be selected toactivate the ketone functional group. When composite structure 101 is apolyetherimide composite, the solutions will be selected to activate theetharimide functional group. When composite structure 101 is apolysulfone composite, the solutions will be selected to activate thesulfone functional group. When composite structure 101 is apolycarbonate composite, the solutions will be selected to activate thecarbonate functional group.

In some applications of the apparatus 100, the composite structure 101may be a composite test specimen (or commonly known as a travelerelement) which is prepared under identical conditions as the structuralcomposite bonding element which is to be tested. Accordingly, thecomposite structure 101 may be selectively removed from the apparatus100 for further analysis after implementation of the apparatus 100.

The functional group analysis module 120, the surface energy analysismodule 121, the chemical-mechanical analysis module 122, and thestructural wettability factor prediction module 123 of the apparatus 100may utilize mathematical algorithms to analyze the bonding surfaceproperties of the bonding surface 102 and formulate a structuralwettability or bonding quality factor (Ø) which may be used to determinewhether the bonding surface 102 is suitable for forming quality bondingwith a structural element in production or repair applications. Theanalysis may be carried out using known principles of polymer chemistry.The functional group analysis module 120 may capture identification ofthe bonding functional groups which each of the solutions 128 impart tothe bonding surface 102.

Surface tension measurements for formulation of the wettabilityprediction factor (bonding quality factor) on the bonding surface 102may be analyzed by the functional group analysis module 120 of theapparatus 100 using equations E1a, E1b, E2a, E2b, E3, E4 and E5. Thesurface tension measurements may be the contact angle of a drop of asolution on the bonding surface 102.

Equation (E1a) is a modified version of Young's equation. Equation (E1a)may be used to calculate surface energy in surface energy analysismodule 121. Equation (E1a) below accounts for the effect of adsorptionof chemical species to the bonding surface 102 on the solid-vaporinterface and liquid-vapor interface:ΔG ₁ ^(G)=−γ_(lv)(1+cos ⊖)  E1a:where,

-   -   ΔG₁ ^(G)=change in surface energy    -   γ_(lv)=surface tension of the liquid    -   ⊖=contact angle of the liquid

In some illustrative examples, the measurements may be a two-dimensionalcontact angle. When the measurements are a two-dimensional contactangle, the Young's equation may be further modified to equation (E1b)receive both measurements of the two-dimensional contact angle.γ_(sv)=γ_(s)−π_(sg)=γ_(lv) cos ⊖+γ_(sl)+γ_(lg) +λtwhere,

-   -   π_(sg)=equilibrium spreading pressure of the gaseous phase on        the solid substrate    -   γ_(sv)=surface tension of the solid vapor interface    -   γ_(s)=surface tension of the solid    -   γ_(lv)=surface tension of the liquid vapor interface    -   ⊖=contact angle taken from a direction normal to the composite        structure; such as direction 134 of FIG. 1    -   γ_(sl)=surface tension of the solid liquid interface    -   γ_(lg)=surface tension of the gaseous liquid interface    -   λ_(t)=a transverse interfacial contact angle taken from a        direction parallel to the composite structure, such as direction        136 of FIG. 1

Equations (E2a) and (E2b) may also be used by surface energy analysismodule 121. Equations (E2a) and (E2b) below describe the equilibriumfilm pressure of a composite structure, the contact angle of which isless than zero.γ_(s)−γ_(sv)=Π_(⊖sv)  E2a:γ_(l)−γ_(lv)=Π_(⊖lv)  E2b:where,

-   -   Π_(⊖sv)=equilibrium spreading pressure of the solid vapor        interface    -   Π_(⊖lv)=equilibrium spreading pressure of the liquid vapor        interface    -   γ_(s)=surface tension of the solid    -   γ_(sv)=surface tension of the solid in equilibrium with the        vapor    -   γ_(l)=surface tension of the liquid    -   γ_(lv)=surface tension of the liquid in equilibrium with the        vapor

The equilibrium spreading pressures above may be included in equation(E3) below representing the solid-liquid interface. Equation (E3) may beused by functional group analysis module 120.γ_(s)−Π_(⊖sv)−γ_(sl)=(γ_(l)−Π_(⊖lv))cos_(⊖)  E3:where,

-   -   Π_(⊖sv)=equilibrium spreading pressure of the solid vapor        interface    -   Π_(⊖lv)=equilibrium spreading pressure of the liquid vapor        interface    -   γ_(s)=surface tension of the solid    -   γ_(sl)=surface tension of the solid liquid interface    -   γ_(l)=surface tension of the liquid

The Wenzel equation (equation E4 below) may be used to describe thecombined influence of hysteresis to measure the accurate contact anglewhere Ω is the ratio of the supposed area to the prepared area outerplane and ⊖ is the contact angle of the liquid on the bonding surface102. In the Wenzel equation, two composite substrates may be provided: afirst, roughened solid which has received surface processing, and asecond solid which has not received surface processing.Ω=cos_(⊖)/cos_(⊖′)  E4:where,

-   -   Ω=a roughness factor    -   ⊖=contact angle that the liquid makes with a roughened surface        of a solid    -   ⊖′=contact angle made by the liquid with a surface of a solid

A modified Fox-Zisman equation may be used by chemical-mechanicalanalysis module 122. The inclusion of a modified Fox-Zisman equation,equation (E5), in analyzing the accuracy of the contact angle ⊖ isimportant in that the equation provides a more accurate estimate ofγ_(s) of the composite structure to be bonded from the plot of ⊖(contact angle) vs. the surface energies. This relationship mayapproximate a straight line described by equation (E5) below. Inequation (E5), W_(I) represents a relevant factor of the Lifshitzequation without incorporating the entirety of the Lifshitz equation.cos_(⊖)=1−b(γ_(l)−γ_(c))W _(I)  E5:where,

-   -   W_(I)=thermodynamic work of adhesion at the slope intercept    -   ⊖=contact angle    -   γ_(c)=critical surface tension    -   γ_(l)=surface tension of the liquid    -   b=slope

As depicted above, γ_(c) is combined with γ_(l) and a relevant factor ofthe modified Lifshitz equation to yield a combined surface energy thatis a consequence of both electromagnetic interactions and contact anglemeasurements from the Fox-Zisman equation. The modified Lifshitzequation may be expressed as:γ_(SL)=γ_(S)+γ_(L)+γ_(V)−2(γ^(P) _(S)*γ^(P) _(L)*γ^(P/2) _(VS))where,

-   -   γ^(P) _(S)=polar component of the solid    -   γ^(P) _(L)=polar component of the liquid    -   γ^(P) _(vs)=polar component of vapor and gaseous phase

The surface energy analysis module 121 of the apparatus 100 may captureidentification of the bonding functional groups of each of the solutions128 on the bonding surface 102 from the functional group analysis module120 and compute the surface tensions of the functional groups as washeretofore described. These data may be transmitted to the computationalchemical-mechanical analysis module 122, which may compile the data andpredict three-dimensional wettability curves for the bonding surface102. The structural wettability factor prediction module 123 may predicta wettability curve factor by comparing the previously-computed bondingsurface properties of the functional groups activated by the solutions128 to the predicted three-dimensional structural wettability curvescomputed by the chemical-mechanical analysis module 122. The structuralwettability factor prediction module 123 may use the wettability curvefactor to determine the bonded repair or bonded structure quality in theform of a bonding quality factor phi (Ø). The structural wettabilityfactor printer 124 may print the bonding quality factor (Ø).

The use of the molecular theory of contact angle in a polar system,which is well-developed in polymer chemistry, can be combined toestimate the surface energy of the composite bonded structuremathematically by cohesive energies of the two phases. Compositestructure and the wettability tensions of the adhesive system can becombined with the polar solutions to develop the individual surfaceenergies close to the individual adhesive systems for bonding with thestructural composite as shown in the cohesive energy equation inequation (6) below:ΔG _(ij) =√{square root over (Δ)}G _(i) ⁰ −ΔG _(j) ⁰=−2√γ_(i)γ_(j) −ΔG_(ij) ^(a) /√{square root over (Δ)}G _(i) ^(c) ΔG _(j) ^(c)=1where liquids i and j are both polar and

-   -   ΔG_(ij)=change in free surface energy for the two polar liquids,        i and j    -   √{square root over (Δ)}G_(i) ⁰=change in individual polar free        energy for liquid i    -   ΔG_(j) ⁰=change in individual polar free energy for liquid j    -   γ_(i)=surface tension of liquid i    -   γ_(j)=surface tension of liquid j    -   ΔG_(ij) ^(a)=initial change in individual polar free energy for        liquids i and j    -   ΔG_(i) ^(c)=initial change in polar free energy of the composite        structure of liquid i    -   ΔG_(j) ^(c)=initial change in polar free energy of the composite        structure of liquid j

Equation (6) may then be used to predict the composite structuralsurface energy and the adhesive wettability tensions to form predictedthree-dimensional curves for the particular composite structures type.The resultant computed experimental exponent is provided as equation (7)and equation (8):Ø(exp)=(γ_(i)+γ_(j−)γ_(ij))/2√(γ_(i)γ_(j))  E7:ΔG _(ij) ^(a)/√(ΔG _(i) ⁰ ΔG _(j) ⁰)=Ø  E8:where,

-   -   γ_(ij)=combined surface tensions for liquids i and j

These thermodynamic cohesion processes and thermodynamic adhesionprocesses represent the idealization of free surface energy modelsemploying thermodynamic terms of:ΔG=2γ−w ^(c).where ΔG ^(C)=−2γ=−w ^(c); and,where ΔG _(ij)=−γ_(ij)−γ_(i−)γ_(j) =−w _(ij) ^(c)

Referring to FIG. 4, a flow diagram 400 which illustrates anillustrative example of the bond surface testing method is shown. Themethod may be carried out in implementation of the apparatus 100 whichwas heretofore described with respect to FIGS. 1 and 2. In block 402,the solution chamber 110 of the apparatus 100 dispenses known solutions128 onto a bonding surface 102 of a composite structure 101. In block404, the functional group analysis module 120 of the apparatus 100 mayidentify functional groups which the solutions 128 activate on thebonding surface 102. In block 406, the structural surface energyanalysis module 121 of the apparatus 100 may analyze surface tensionsand pressures on the bonding surface 102. In block 408, thechemical-mechanical analysis module 122 of the apparatus 100 may predictthree-dimensional wettability curves based on the bonding surfaceproperty data obtained from the functional group analysis module 120 andthe surface energy analysis module 121. In block 410, the structuralwettability factor prediction module 123 of the apparatus 100 maypredict a bonding quality factor by matching the surface energies of thefunctional groups on the bonding surface with the three-dimensionalwettability curves.

In the event that the bonding quality factor predicted in block 410 isless than one (block 412), the method may return to block 402. In theevent that the bonding quality factor predicted in block 410 is greaterthan one (block 414), durable bonding is achievable and production isready in block 416. In block 418, the structural wettability factorprinter 124 of the apparatus 100 may print out quality controlparameters for the structure to be bonded.

Referring next to FIGS. 1-3A and 5, a functional block diagram 500 whichillustrates exemplary operation of an illustrative example of the bondsurface testing apparatus 100 is shown in FIG. 5. In block 502, thestand-offs 117 (FIGS. 1 and 2) of the apparatus 100 may be adjusted onthe bonding surface 102 of the composite structure 101. In someapplications, the stand-offs 117 may be a distance allowing the solutionto clear the surface tension. In block 504, the apparatus 100 may belocated on the bonding surface 102. The wettability tension device maybe placed next to stand-offs 117 to minimize surface contact andoptimize separation. The stand-offs 117 may be adjusted to minimizesurface contact and optimize separation on the bonding surface 102. Inblock 506, the apparatus 100 may be activated. Accordingly, amicro-liter volume of each solutions 128 may be deposited from each ofthe solution containers 111 of the solution chamber 110 onto the bondingsurface 102. In block 508, after all solutions 128 have been depositedonto the bonding surface 102, the apparatus 100 may initiate ananalytical mode 509 in which surface measurement images are taken withan onboard camera (not shown). As shown in FIG. 3A, in someapplications, onboard LEDs 132 may illuminate the bonding surface 102.FIG. 3A is a view within section 3-3 of FIG. 2. As depicted, onboardLEDs 132 are carried by information capture module 116. In some otherexamples, onboard LEDs 132 may be attached to a different module of theapparatus 100.

As shown in FIG. 5, in some embodiments, the analytical mode 509 mayinclude operation of the solution chamber 110 to deposit the solutions128 onto the bonding surface 102 (block 510); functional groupidentification by the functional group analysis module 120 (block 512);structural surface energy analysis by the structural surface energyanalysis module 121 (block 514); computation of three-dimensionalwettability curves by the chemical-mechanical analysis module 122 (block516) based on the functional group analysis and the structural surfaceenergy analysis; prediction of a wettability curve or bonding qualityfactor by the structural wettability factor prediction module 123 (block518); and printing of the structural wettability factor with certifiableresults by the structural wettability factor printer 124 (block 520).The certifiable results may indicate whether the surface is ready forbonding or surface preparation is required prior to bonding.

If the structural wettability factor predicted in block 518 and printedin block 520 is less than one, the method may return (block 522) toblock 502 and blocks 504-520 may be repeated. If the structuralwettability factor is greater than one, the method may proceed to block524 in which durable bonding is achievable and bonding production canproceed.

Referring next to FIG. 5A, a flow diagram 500A which summarizes anillustrative example of the bond surface testing method is shown. Inblock 502A, known solutions are provided. If a composite structure 101to be tested is an epoxide composite, a solution may be dimethyl sulfuroxide. If composite structure 101 to be tested is a bismaleimide (BMI)composite, a solution may be a non-fluorinated compound. For other typesof composite structure 101, a solution may be a fluorinated compound. Inblock 504A, functional groups on a bonding surface are activated bydispensing the solutions onto the bonding surface. In block 506A,bonding surface properties on the bonding surface are analyzed. In someembodiments, analyzing bonding surface properties may includeidentifying functional groups on the bonding surface. In someembodiments, analyzing bonding surface properties may include analyzingsurface energies on the bonding surface. In some embodiments, analyzingbonding surface properties may include predicting three-dimensionalwettability curves based on the bonding surface properties. In block508A, a structural wettability factor is predicted based on the bondingsurface properties. In some embodiments, predicting a structuralwettability factor based on the bonding surface properties may includepredicting a structural wettability factor by matching thethree-dimensional wettability curves with the surface energies on thebonding surface.

Referring next to FIG. 5B, a flow diagram 500B which illustratesoperation of an illustrative example of the bond surface testingapparatus is shown. In block 502B, the method begins by providing aplurality of solutions. In block 504B, the method may activatefunctional groups on a bonding surface by dispensing the plurality ofsolutions onto the bonding surface, in which at least one solution ofthe plurality of solutions is dispensed in a non-circular shape onto thebonding surface. In block 506B, the method may analyze bonding surfaceproperties on the bonding surface. In some embodiments, analyzingbonding surface properties may include identifying functional groups onthe bonding surface. In some embodiments, analyzing bonding surfaceproperties may include analyzing surface energies on the bondingsurface. In some embodiments, analyzing bonding surface properties mayinclude predicting three-dimensional wettability curves based on thebonding surface properties. In block 508B, the method may predict astructural wettability factor based on the bonding surface properties.In some embodiments, predicting a structural wettability factor based onthe bonding surface properties may include predicting a structuralwettability factor by matching the three-dimensional wettability curveswith the surface energies on the bonding surface. Afterwards the processmay terminate.

Referring next to FIGS. 6 and 7, embodiments of the disclosure may beused in the context of an aircraft manufacturing and service method 78as shown in FIG. 6 and an aircraft 94 as shown in FIG. 7. Duringpre-production, exemplary method 78 may include specification and design80 of the aircraft 94 and material procurement 82. During production,component and subassembly manufacturing 84 and system integration 86 ofthe aircraft 94 takes place. Thereafter, the aircraft 94 may go throughcertification and delivery 88 in order to be placed in service 90. Whilein service by a customer, the aircraft 94 may be scheduled for routinemaintenance and service 92 (which may also include modification,reconfiguration, refurbishment, and so on).

Each of the processes of method 78 may be performed or carried out by asystem integrator, a third party, and/or an operator (e.g., a customer).For the purposes of this description, a system integrator may include,without limitation, any number of aircraft manufacturers andmajor-system subcontractors; a third party may include, withoutlimitation, any number of vendors, subcontractors, and suppliers; anoperator may be an airline, leasing company, military entity, serviceorganization, and so on.

As shown in FIG. 7, the aircraft 94 produced by exemplary method 78 mayinclude an airframe 98 with a plurality of systems 96 and an interior103. Examples of high-level systems 96 include one or more of apropulsion system 105, an electrical system 104, a hydraulic system 106,and an environmental system 108. Any number of other systems may beincluded. Although an aerospace example is shown, the principles of theinvention may be applied to other industries, such as the automotiveindustry.

The apparatus embodied herein may be employed during any one or more ofthe stages of the production and service method 78. For example,components or subassemblies corresponding to production processcomponent and subassembly manufacturing 84 may be fabricated ormanufactured in a manner similar to components or subassemblies producedwhile the aircraft 94 is in service. In other words, composite structure101 in FIG. 1 may be used to form a component or subassembly duringproduction process component and subassembly manufacturing 84. Thebonding surface 102 in FIG. 1 of composite structure 101 may be testedduring production process component and subassembly manufacturing 84.Also one or more apparatus embodiments may be utilized during theproduction stages material procurement 82 and system integration 86, forexample to test bonding surface 102 of composite structure 101. Use ofone or more apparatus or method embodiments may expedite assembly of orreduce the cost of an aircraft 94. Similarly, one or more apparatusembodiments may be utilized while the aircraft 94 is in service, forexample and without limitation, during maintenance and service 92. Forexample, the apparatus or method embodiments may be used to test thebonding surface 102 of a replacement or repair composite structure 101during maintenance and service 92.

The disclosure is generally directed to a bond surface testing apparatusfor testing bonding suitability of a bonding surface. An illustrativeembodiment of the apparatus includes a solution chamber; a plurality ofsolutions in the solution chamber, the solution chamber configured todispense the solutions onto the bonding surface; an information capturemodule carried by the solution chamber and configured to captureinformation relating to bonding surface properties of the bondingsurface; at least one analysis module interfacing with the informationcapture module and configured to analyze the bonding surface propertiesof the bonding surface; and a structural wettability factor predictionmodule interfacing with the at least one analysis module and configuredto predict a structural wettability factor based on the bonding surfaceproperties.

In some embodiments, the bond surface testing apparatus may include asolution chamber; a plurality of solutions in the solution chamber, thesolution chamber configured to dispense the solutions onto the bondingsurface; a pair of stand-offs configured to engage the bonding surface;an information capture module carried by the stand-offs and configuredto capture information relating to bonding surface properties of thebonding surface; a data transfer pathway interfacing with theinformation capture module; a plurality of analysis modules interfacingwith the data transfer pathway and configured to analyze the bondingsurface properties of the bonding surface; and a structural wettabilityfactor prediction module interfacing with the data transfer pathway andconfigured to predict a structural wettability factor based on thebonding surface properties.

The disclosure is further generally directed to a bond surface testingmethod. An illustrative embodiment of the method includes providing aplurality of solutions; activating functional groups on a bondingsurface by dispensing the plurality of solutions onto the bondingsurface; analyzing bonding surface properties on the bonding surface;and predicting a structural wettability factor based on the bondingsurface properties.

In one illustrative example, a bond surface testing apparatus fortesting bonding suitability of a bonding surface is presented. The bondsurface testing apparatus comprises a solution chamber; a plurality ofsolutions in the solution chamber, the solution chamber configured todispense the solutions onto the bonding surface; an information capturemodule carried by the solution chamber and configured to captureinformation relating to bonding surface properties of the bondingsurface; at least one analysis module interfacing with the informationcapture module and configured to analyze the bonding surface propertiesof the bonding surface; and a structural wettability factor predictionmodule interfacing with the at least one analysis module and configuredto predict a structural wettability factor based on the bonding surfaceproperties.

In some examples, the apparatus further comprises a structuralwettability factor printer interfacing with the structural wettabilityfactor prediction module and configured to print the structuralwettability factor. In some examples, the apparatus further comprises aplurality of solution containers in the solution chamber and wherein theplurality of solutions are contained in the plurality of solutioncontainers, respectively. In some examples, the apparatus furthercomprises a plurality of solution containers in the solution chamber andwherein the plurality of solutions are contained in the plurality ofsolution containers, respectively; and a plurality of microfluidicpipettes and actuators interfacing with the plurality of solutioncontainers, respectively, and be configured to dispense the solutionsonto the bonding surface. In some examples, the at least one analysismodule comprises a functional group analysis module configured toidentify functional groups on the bonding surface. In some examples, theat least one analysis module comprises a functional group analysismodule configured to identify functional groups on the bonding surfaceand the at least one analysis module comprises a surface energy analysismodule configured to analyze surface energies of the functional groupson the bonding surface. In some examples, the at least one analysismodule comprises a functional group analysis module configured toidentify functional groups on the bonding surface; the at least oneanalysis module comprises a surface energy analysis module configured toanalyze surface energies of the functional groups on the bondingsurface; and the at least one analysis module comprises achemical-mechanical analysis module configured to predictthree-dimensional wettability curves based on data from the functionalgroup analysis module and the surface energy analysis module. In someexamples, the at least one analysis module comprises a functional groupanalysis module configured to identify functional groups on the bondingsurface; the at least one analysis module comprises a surface energyanalysis module configured to analyze surface energies of the functionalgroups on the bonding surface; the at least one analysis modulecomprises a chemical-mechanical analysis module configured to predictthree-dimensional wettability curves based on data from the functionalgroup analysis module and the surface energy analysis module; and thestructural wettability factor prediction module configured to predictthe structural wettability factor by matching the three-dimensionalwettability curves with the surface energies of the functional groups onthe bonding surface.

In another illustrative example, a bond surface testing apparatus fortesting bonding suitability of a bonding surface is presented. The bondsurface testing apparatus comprises a solution chamber; a plurality ofsolutions in the solution chamber, the solution chamber configured todispense the solutions onto the bonding surface; a pair of stand-offsconfigured to engage the bonding surface; an information capture modulecarried by the stand-offs and configured to capture information relatingto bonding surface properties of the bonding surface; a data transferpathway interfacing with the information capture module; a plurality ofanalysis modules interfacing with the data transfer pathway andconfigured to analyze the bonding surface properties of the bondingsurface; and a structural wettability factor prediction moduleinterfacing with the data transfer pathway and configured to predict astructural wettability factor based on the bonding surface properties.

In some examples, the apparatus further comprises a structuralwettability factor printer interfacing with the data transfer pathwayand configured to print the structural wettability factor In someexamples, the apparatus further comprises a plurality of solutioncontainers in the solution chamber and wherein the plurality ofsolutions are contained in the plurality of solution containers,respectively. In some examples, the apparatus further comprises aplurality of solution containers in the solution chamber wherein theplurality of solutions are contained in the plurality of solutioncontainers, respectively, and a plurality of microfluidic pipettes andactuators interfacing with the plurality of solution containers,respectively, and configured to dispense the solutions onto the bondingsurface.

In some examples, the plurality of analysis modules comprises afunctional group analysis module configured to identify functionalgroups on the bonding surface. In some examples, the plurality ofanalysis modules comprises a functional group analysis module configuredto identify functional groups on the bonding surface; and whereinplurality of analysis modules comprises a surface energy analysis moduleconfigured to analyze surface energies of the functional groups on thebonding surface. In some examples, the plurality of analysis modulescomprises a functional group analysis module configured to identifyfunctional groups on the bonding surface; wherein plurality of analysismodules comprises a surface energy analysis module configured to analyzesurface energies of the functional groups on the bonding surface; andwherein the plurality of analysis modules comprises achemical-mechanical analysis module configured to predictthree-dimensional wettability curves based on data from the functionalgroup analysis module and the surface energy analysis module. In someexamples, In some examples, the plurality of analysis modules comprisesa functional group analysis module configured to identify functionalgroups on the bonding surface; wherein plurality of analysis modulescomprises a surface energy analysis module configured to analyze surfaceenergies of the functional groups on the bonding surface; wherein theplurality of analysis modules comprises a chemical-mechanical analysismodule configured to predict three-dimensional wettability curves basedon data from the functional group analysis module and the surface energyanalysis module; and wherein the structural wettability factorprediction module is configured to predict the structural wettabilityfactor by matching the three-dimensional wettability curves with thesurface energies of the functional groups on the bonding surface.

In one illustrative example, a bond surface testing method is presented.The method comprises providing a plurality of solutions; activatingfunctional groups on a bonding surface by dispensing the plurality ofsolutions onto the bonding surface; analyzing bonding surface propertieson the bonding surface; and predicting a structural wettability factorbased on the bonding surface properties. In some examples, the analyzingbonding surface properties comprises identifying functional groups onthe bonding surface. In some examples, the analyzing bonding surfaceproperties comprises identifying functional groups on the bondingsurface and analyzing surface energies on the bonding surface. In someexamples, the analyzing bonding surface properties comprises identifyingfunctional groups on the bonding surface, analyzing surface energies onthe bonding surface, and predicting three-dimensional wettability curvesbased on the bonding surface properties.

A bond surface testing apparatus includes a solution chamber; aplurality of solutions in the solution chamber, the solution chamberconfigured to dispense the solutions onto a bonding surface; aninformation capture module carried by the solution chamber andconfigured to capture information relating to bonding surface propertiesof the bonding surface; at least one analysis module interfacing withthe information capture module and configured to analyze the bondingsurface properties of the bonding surface; and a structural wettabilityfactor prediction module interfacing with the at least one analysismodule and configured to predict a structural wettability factor basedon the bonding surface properties.

Although the embodiments of this disclosure have been described withrespect to certain exemplary embodiments, it is to be understood thatthe specific embodiments are for purposes of illustration and notlimitation, as other variations will occur to those of skill in the art.

What is claimed is:
 1. A bond surface testing apparatus for testingbonding suitability of a bonding surface, comprising: a solutionchamber; a plurality of solution containers located in the solutionchamber; a plurality of microfluidic pipettes configured such that eachsolution container in the plurality of solution containers comprises amicrofluidic pipette of the plurality of microfluidic pipettes such thata number of the plurality of microfluidic pipettes each comprise across-section, substantially perpendicular to a central axisrespectively of the each microfluidic pipette, being non-circular andconfigured such that in response to a dispensation, of a selectedsolution from the each microfluidic pipette, a drop, on the bondingsurface, of the dispensation comprises a selected shape that comprises aplanform that comprises a non-circular shape; and an information capturemodule physically associated with the solution chamber and configured tocapture information relating to bonding properties of the bondingsurface.
 2. The bond surface testing apparatus of claim 1, wherein theinformation relating to the bonding properties of the bonding surfacecomprises a two-dimensional contact angle.
 3. The bond surface testingapparatus of claim 1, wherein the information capture module comprises anumber of optical sensors.
 4. The bond surface testing apparatus ofclaim 1 further comprising: at least one analysis module interfacingwith the information capture module and configured to analyze thebonding properties of the bonding surface; and a structural wettabilityfactor prediction module interfacing with the at least one analysismodule and configured to predict a structural wettability factor basedon the bonding properties.
 5. The bond surface testing apparatus ofclaim 4, wherein the at least one analysis module comprises a functionalgroup analysis module configured to identify functional groups on thebonding surface.
 6. The bond surface testing apparatus of claim 5,wherein the at least one analysis module further comprises a surfaceenergy analysis module configured to analyze surface energies of thefunctional groups on the bonding surface.
 7. The bond surface testingapparatus of claim 6, wherein the at least one analysis module furthercomprises a chemical-mechanical analysis module configured to predictthree-dimensional wettability curves based on data from the functionalgroup analysis module and the surface energy analysis module.
 8. Thebond surface testing apparatus of claim 7, wherein the structuralwettability factor prediction module is configured to predict thestructural wettability factor by matching the three-dimensionalwettability curves with the surface energies of the functional groups onthe bonding surface.
 9. A bond surface testing apparatus for testingbonding suitability of a bonding surface, comprising: a solutionchamber; a plurality of solution containers located in the solutionchamber; a plurality of microfluidic pipettes configured such that eachsolution container in the plurality of solution containers comprises amicrofluidic pipette of the plurality of microfluidic pipettes such thata number of the plurality of microfluidic pipettes each comprise across-section, substantially perpendicular to a central axisrespectively of the each microfluidic pipette, being non-circular andconfigured such that in response to a dispensation, of a selectedsolution from the each microfluidic pipette, a drop of the dispensation,on the bonding surface, comprises a selected shape that comprises aplanform that comprises a non-circular shape; a plurality of solutionsin the solution chamber, each microfluidic pipette configured todispense a solution in the plurality of solutions onto the bondingsurface; a plurality of stand-offs configured to engage the bondingsurface; an information capture module carried by the plurality ofstand-offs and configured to capture information relating to bondingproperties of the bonding surface; a data transfer pathway interfacingwith the information capture module; a plurality of analysis modulesinterfacing with the data transfer pathway and configured to analyze thebonding properties of the bonding surface; and a structural wettabilityfactor prediction module interfacing with the data transfer pathway andconfigured to predict a structural wettability factor based on thebonding surface properties.
 10. The bond surface testing apparatus ofclaim 9, wherein the information relating to the bonding properties ofthe bonding surface comprises a two-dimensional contact angle.
 11. Thebond surface testing apparatus of claim 9, wherein the informationcapture module comprises a number of optical sensors.
 12. The bondsurface testing apparatus of claim 9, wherein the plurality of analysismodules comprises a functional group analysis module configured toidentify functional groups on the bonding surface.
 13. The bond surfacetesting apparatus of claim 12, wherein the plurality of analysis modulesfurther comprises a surface energy analysis module configured to analyzesurface energies of the functional groups on the bonding surface. 14.The bond surface testing apparatus of claim 13, wherein the plurality ofanalysis modules comprises a chemical-mechanical analysis moduleconfigured to predict three-dimensional wettability curves based on datafrom the functional group analysis module and the surface energyanalysis module.
 15. The bond surface testing apparatus of claim 14,wherein the structural wettability factor prediction module isconfigured to predict the structural wettability factor by matching thethree-dimensional wettability curves with the surface energies of thefunctional groups on the bonding surface.
 16. A bond surface testingmethod, comprising: providing a plurality of solutions; activating afunctional group on a bonding surface by dispensing a solution from theplurality of solutions onto the bonding surface, via dispensing at leastone solution of the plurality of solutions comprising a planformcomprising a non-circular shape onto the bonding surface via at leastone microfluidic pipette associated with the solution, the microfluidicpipette comprising a cross-section, substantially perpendicular to acentral axis respectively of the each microfluidic pipette, thecross-section being non-circular and producing, via dispensing thesolution from the microfluidic pipette, a drop of the solution, on thebonding surface, comprising a selected shape comprising the planformcomprising the non-circular shape; analyzing bonding properties on thebonding surface; and predicting a structural wettability factor based onthe bonding properties.
 17. The bond surface testing method of claim 16further comprising: capturing information relating to the bondingproperties of the bonding surface, wherein the information relating tothe bonding properties of the bonding surface comprises atwo-dimensional contact angle.
 18. The bond surface testing method ofclaim 16, wherein analyzing the bonding properties comprises identifyingthe functional groups on the bonding surface.
 19. The bond surfacetesting method of claim 18, wherein analyzing the bonding propertiesfurther comprises analyzing surface energies on the bonding surface. 20.The bond surface testing method of claim 19, wherein analyzing thebonding properties further comprises predicting three-dimensionalwettability curves based on the bonding properties.